The present invention relates to the art of personal mobility vehicles, particularly vehicles for the physically impaired. Particular application is found in children's wheelchairs which will have to be adaptable as the child grows. However, it is to be appreciated that the present invention may also be applicable to wheelchairs for adults and may be utilized to custom fit wheelchairs to adults, may enable the chair to be utilized by adults or children of different sizes, or may be applicable to other vehicles.
Hitherto, wheelchairs have been manufactured in various sizes to accommodate children as they grow. Manufacturing children's chairs in only fixed sizes requires frequent replacement of the entire chair and a large financial burden on parents. Accordingly, children's chairs have commonly been constructed to accommodate size alterations, thus enabling the child to use the chair over a wider range of physiological development.
In one solution, seats of different sizes have been selectively mounted on a conventional, fill size wheelchair frame. However, because the child's seat tended to be much shorter than a conventional frame, the frame extended forward significantly passed the child's feet. This excessive forward extension created difficulty in manoeuvring the chair and pulling up to tables and desks.
From EP 08885605 (Invacare) is a wheelchair suggested where the adjustments are carried out by adjusting the features such as the wheel bearings along rails provided in a sub frame. The sub frame together with the rails for adjusting the wheel base and wheel distance are provided as steel profiles which after adjustment must be refastened by means of bolts. Furthermore, a quite substantial number of parts needs to be adjusted in order to alter/adjust the size of the wheelchair which in turn allows for the occurrence of mistakes or other defaults.
Yet another adjustable wheelchair is suggested in U.S. Pat. No. 5,320,373 (Robertson et al.) wherein two substantially rigged side frames are provided in order to fasten the front and rear wheels in either side. The distance between the wheels in the driving direction of the wheelchair is not adjustable. The point of gravity may be adjusted by mounting the seat in different positions in relation to the rigged frame holding the two wheel axles. The tilt of the seat is adjusted by further displacing the two bearing arms arranged in each rigged side frame such that the tilting of the seat cannot be carried out stepless or while a person is seated in the chair. Furthermore, transfer of the point of gravity in relation to the driving direction is not possible since the distance between the wheels is fixed whereby the chair has a firm wheel base.